We’ve all heard it, you may well have even said it, or been told it.
“I think I need to strengthen my core” or “Your back pain is coming from your weak core”
Exercising the core, or trunk muscles, has long been recommended to prevent injuries and even help us improve in our sports performance. This, however, has actually never really been proven. In fact, only a small correlation between trunk muscle strength and athletic performance has ever been shown. The evidence for core stability programs to assist back pain is similarly low.
So, if you’ve been told you have a weak core and are a little confused with the mixed message; here are a few facts from the critical analysis of the evidence, conducted by Wirth et al (2016)!
  • The small ‘lower back stabilising muscles’ do not have the capacity to stabilise the spine in isolation. This load is absorbed by the large erector spinae muscle, as only they can counteract gravity
  • There is no specific isolation of small or large muscles, but rather an interaction of both depending on the tasks required
  • You can’t switch off a muscle. Painful muscles have been shown to be less active, which over a long period of time, may result in pain and dysfunction. This, however, does not occur overnight or only to a few select muscles (e.g. multifidus and transverse abdominis)
  • Claims that ‘core’ programs are better at developing strength than other methods (e.g. barbell training) have never been investigated
  • Rotational training for trunk muscle development is questionable, due to potentially high forces transmitted through discs. Counter-rotation or resisting rotation is a safer alternative

Ok, so now we’re starting to build a snapshot of some of the evidence. But what about those out there that claim to be doing something ‘different’? They may claim their method is based on ‘function’, or is somehow more ‘specific’, which gets you results FAST!
By now we’ve all probably seen this guy before… He is the product of typing “functional core training” into google.
He’ll tell you that he, or his Guru Fitness instructor, recommends this exercise for “building a wicked core, Bro”, or “it’s really functional!”
I can honestly tell you I have never found myself in a situation where I have been required to stand on a ball or rotational disc, in my sporting or personal life…
The good thing is evidence based research is here to help provide some clarity! Wirth et al (2016) concluded that there is “no evidence to support training on unstable surfaces”. In fact, training on unstable surfaces instead produced exercises which had; decreased load, reduced exercise depth and favoured high repetitions.
How do you improve muscular strength if you’re compromising on all the important stuff?
Exercise should mimic, or be as close too, everyday life or sport movements as possible. A simple trick is to look at the core exercises you’ve commonly been told and ask yourself ‘do they look similar to what I’m trying to achieve?’
You could argue that the central nervous system (CNS), when exposed to unstable conditions, adapts to activate the core muscles under different circumstances, hence improving muscular coordination.
This argument, however, could be used for any exercise, unstable or not, and there have not been any studies showing a positive, strong relationship between unstable conditions and athletic performance or improved core strength.
I think the final sentence of the review sums it up nicely;
 “We recommend the use of classical strength-training exercises as these provide the necessary stimuli to induce the desired adaptations.”
So get out there, lift heavy things (safely), get strong and be skepitcal of anyone selling you the new, greatest thing!
Wirth, K., Hartmann, H., Mickel, C., Szilvas, E., Keiner, M., & Sander, A. (2016). Core Stability in Athletes: A Critical Analysis of Current Guidelines. Sports Medicine, 1-14.